Gene therapy has emerged as a promising strategy for bone repair and regeneration. The key to its success is to deliver the genes of interest to the target bone fracture site that can be expressed at suitable levels. Both ex vivo and in vivo gene therapy strategies have been proposed. In the ex vivo strategy, target cells such as mesenchymal stem cells (MSCs) are harvested from the patient, genes of interest such as bone morphogenetic protein (BMP) gene carried by a vector are delivered to the target cells under in vitro conditions, and then the target cells are implanted into the site of injury. In the in vivo strategy, genes of interest carried by a vector are delivered to the target site by intravenous injection or directly implanted to the site of injury. Thus an ideal gene delivery vector should be bone-seeking and cell-targeting. Our long-term goal is to integrate the naturally evolved biological recognition and nanotechnology to build target-specific non-viral gene vectors for bone regeneration by gene therapy. The objective of this particular application is to form and evaluate bone-seeking and cell-targeting non-viral vectors for virus-like site-specific delivery of BMP-2 gene. The overall hypothesis of this project is that bone-seeking and cell-targeting peptides identified by a virus-based selection technology can biomimetically self-assemble with the BMP-2 gene-bearing nanoparticles to form bone-seeking and cell-targeting virus-like non-viral vectors for site-specific BMP-2 gene delivery. The following specific aims are designed to test our central hypotheses: (1) Selection of bone-seeking and cell-targeting peptides from a virus-based random peptide library;(2) Biomimetic assembly of BMP-2-gene-bearing nanoparticles and the bone-seeking and cell-targeting peptides to form bone-seeking and cell-targeting non-viral vectors;and (3) Evaluation of in vitro BMP-2 gene delivery by the bone-seeking and cell-targeting non-viral vectors. Successful completion of this project will discover a bone-seeking and cell-targeting peptide and produce a novel non-viral gene delivery vector that exhibits high transfection efficiency and bone cell/tissue-specificity. Such vectors can be used for the repair and regeneration of musculoskeletal tissues and treatment of genetic based bone diseases such as osteogenesis imperfecta by gene therapy.